Yutyrannus, the Feathered Giant

The latest from the amazing fossil beds of northeast China that have produced so many feathered dinosaurs:

A newly discovered giant feathered dinosaur—a distant cousin of Tyrannosaurus rex—sported a fine down coat, making it the largest feathered animal known to have lived, scientists say. Paleontologists already knew that some members of the group of dinosaurs to which T. rex belonged, called theropods, were feathered. But most of the known feathered dinos were relatively small.

"It was a question mark whether larger relatives of these small theropods were also feathered," said study team member Corwin Sullivan, a paleontologist at the Chinese Academy of Sciences in Beijing. "We simply didn't have data either way, because soft-tissue preservation of any kind is so rare."

Now three tyrannosauroid fossils—one adult and two juveniles—offer clear proof that giant theropods could also be feathered. Their feathers were simple filaments, more like the fuzzy down of a modern baby chick than the stiff plumes of an adult bird.

The new dinosaur species, detailed in this week's issue of the journal Nature, has been named Yutyrannus huali—a Latin-Mandarin mash-up that means "beautiful feathered tyrant." . . . The researchers estimate that the adult Yutyrannus would have measured about 30 feet (9 meters) long and weighed about 1.5 tons (1,400 kilograms).

The discoverers speculate that Yutyrannus had feathers to keep warm, since it lived 125 million years ago in a rather cold era; a sort of woolly mammoth of dinosaurs. The feathers are simple threads, 6 to 8 inches (15 to 20 cm) long.

A Yutyrannus skull. The picture at top shows a group of Yutyrannus and smaller Beipiaosaurus. Yutyrannus would have only have been about 1/5 the size of T. rex, so not very big by dinosaur standards, but still the largest feathered animal known. A debate has raged for decades over whether T. rex had feathers, and some people are saying this find makes it more likely that it did. Think of all the models, paintings, and movies that would become instantly out of date if T. rex was a feathered beast.